Hmm...Meganium d may be an excellent card of the format right now, but this Meganium is far from 'wrong' or 'awful'.
Pros:
130 HP is decent for a S2, and while its weakness to Fire puts it in harms way against many decks (Infernape, Magmortar), it is only +30 w/o Lake Boundry, so not terrible. Without Pluspowers/Strength Charms, or a LB, it isn't OHKO-able by either Infernape or Magmortar, so that is saying something.
Its first attack...come on, you can't deny that it is good. For a single Grass energy, you do 20 damage PLUS have an excellent chance at afflicting your opponent with a crippling condition, or conditions. While this is very 'flippy' and unreliable, chances are it will totally screw with your opponent. If you play it with Skarmory ex, or better yet, Ariados MT, you also trap them into dealing with one or more of the conditions. This can give you time to set-up, or recover, two very important things.
Its second attack may be weak, but Fire Pokemon still see play. Gardevoir ex d, Latias ex d, Latias d, Infernape, Magmortar, and more all see fair amounts of play (varying by location). It is a nice Scramble move, and is definitely helpful in certain situations. However, Meganium's first attack is why you would want to play this card, so its second attack is purely back-up.
Its resistance to Water isn't as good as Meganium d's, but it is still a resistance, so yeah.
Cons:
Weakness is bad. While only +30, it is a costly one.
Retreat Cost is bad as well. There is no Fluffy Berry, Mantine, or Phoebe's Stadium to help this one, so you have to rely on Switch/Warp Point.
It is a S2, so by nature, it is slower. HOWEVER, its best attack only costs one energy, so you could potentially be annoying your opponent T1 if you go first.
Overall, this is not a bad card. It got me second at a BR, and I love it. Absolutely love it. It is very good when COMBINED with Meganium d. Just a very loveable card, in my opinion (you do have to have an affection for 'flippy-ness', though).
Modified - 7.5/10
Limited - 8/10 (IF you get the pre-evolutions, mind you)